Egyptian state media say clashes in the Sinai region have killed at least six people and wounded 21 more.
The state-run MENA news agency reported Saturday that the dead include a policeman and a military officer.
The unrest began Friday when at least 100 armed men rode into the Sinai town of el-Arish and tried to storm a police station. Authorities have not identified the attackers but witnesses say some waved flags with Islamic slogans as they fired shots into the air. A state media report said security forces have arrested at least four suspects.
On Saturday, gunmen attacked a pipeline once used to supply gas to Israel - the fifth pipeline assault in the Sinai region since February.
A state media report says masked men launched rocket-propelled grenades at the al-Shulaq natural gas terminal. The report says the pipe was hit but the line contained no gas and had not been operating for some time.
In a separate development, an Egyptian appeals court said the August 3rd trial of former President Hosni Mubarak will be held at the Cairo Police Academy, instead of the city's Convention Center.
Appeals Court President Abdel Aziz Omar announced the change on Saturday, saying it will be easier to maintain security for the former president at the new venue.
Mr. Mubarak faces a possible death sentence if convicted of unleashing police on demonstrators that drove him from office during an 18-day uprising in February. At least 840 people were killed in the revolt.
Some information for this report was provided by AP, AFP and Reuters.